Police negotiated through a four-inch ventilation pipe Friday with a gunman holding a 5-year-old boy hostage in an underground bunker in rural southeast Alabama, four days after the man shot and killed a bus driver while abducting the boy from a school bus.

Jimmy Lee Dykes, 65, remained holed up with the boy in a bunker police said is equipped with food, electricity and a working TV near a rural road in tiny Midland City. Police have provided no motive for the shooting or abduction, but neighbors have described Dykes as a menacing figure who angrily confronted them over minor incidents.

The boy, identified by neighbors as Ethan, has cried for his parents, according to Midland City Mayor Virgil Skipper. Authorities have used the ventilation pipe to provide medication for the boy. He has Asperger’s syndrome and attention deficit hyperactivity disorder, according to Alabama state Rep. Steve Clouse, who said he had spoken with the boy’s mother.

Dale County Sheriff Wally Olson told reporters that the boy had not been harmed. Ethan was apparently taken at random by the gunman, who first said he wanted to take two boys between 6 and 8 years old before shooting the bus driver. Authorities have said they do not believe Dykes knew the abducted boy.

Police have provided little information about their communications with Dykes, and have not disclosed what type of weapons he may have.

The police chief of a neighboring town indicated Friday that the standoff could continue indefinitely because the gunman claimed to have spent long periods in the bunker.

“He will have to give up sooner or later because (authorities) are not leaving,” James Arrington, police chief of nearby Pinckard, told the Associated Press. “It’s pretty small, but he’s been known to stay in there eight days.”

Arrington said the shelter is about 4 feet underground, 8 feet wide and 8 feet long. The ventilation pipe stretches about 60 feet, according to authorities.

Dykes, who officials said is a retired truck driver and Navy veteran, has been described by neighbors as a threatening figure. They said he once beat a dog to death with a lead pipe for straying onto his property and has fired shots at residents. He was sometimes seen patrolling his property at night with a flashlight and gun, or digging with a shovel during the day.

Dykes was scheduled to appear in court on Wednesday to answer a charge of menacing a neighbor, Claudia Davis. She has told reporters that Dykes screamed at her and fired shots at her, her son and infant grandson after he claimed their pickup truck was damaging a makeshift speed bump on a dirt road. No one was hurt.

On Tuesday afternoon, a gunman boarded a school bus bringing more than 20 children home. According to officials, quoting the children, Dykes fired several times, killing the driver, Charles Albert Poland Jr., who tried to block the gunman’s way. The gunman then grabbed Ethan and fled to the bunker near Dykes’ home.

Tim Byrd, chief investigator with the Dale County Sheriff’s Office, described Dykes as a survivalist with “anti-American” views, according to the Southern Poverty Law Center, a civil rights group in Montgomery, Ala.

“His friends and his neighbors stated that he did not trust the government, that he was a Vietnam vet, and that he had PTSD,” Byrd said, according to the center. “He was standoffish, didn’t socialize or have any contact with anybody. He was a survivalist type.”

Neighbors have told reporters that Dykes lived in a camping trailer on the dirt road, not far from the site of the bunker.

James Davis Jr., the neighbor’s son allegedly menaced by Dykes, has said in TV interviews that Dykes told him he built it as a tornado shelter.